Objective To identify structural gray matter (GM) differences between persistent violent offenders who meet criteria for antisocial personality disorder and the syndrome of psychopathy (ASPD+P) and those meeting criteria only for ASPD (ASPD–P).

Results Offenders with ASPD+P displayed significantly reduced GM volumes bilaterally in the anterior rostral prefrontal cortex (Brodmann area 10) and temporal poles (Brodmann area 20/38) relative to offenders with ASPD–P and nonoffenders. These reductions were not attributable to substance use disorders. Offenders with ASPD–P exhibited GM volumes similar to the nonoffenders.

Conclusions Reduced GM volume within areas implicated in empathic processing, moral reasoning, and processing of prosocial emotions such as guilt and embarrassment may contribute to the profound abnormalities of social behavior observed in psychopathy. Evidence of robust structural brain differences between persistently violent men with and without psychopathy adds to the evidence that psychopathy represents a distinct phenotype. This knowledge may facilitate research into the etiology of persistent violent behaviour.

Now this is indeed quite interesting.

Most violent crimes are committed by a small group of persistent male offenders with ASPD. Approximately half of male prisoners in England and Wales will meet diagnostic criteria for ASPD, characterized by emotional instability, impulsivity and high levels of mood and anxiety disorders.

However, about one third of such men will meet additional diagnostic criteria for psychopathy (ASPD+P). They are characterised by a lack of empathy and remorse, and use aggression in a planned way to secure what they want (status, money etc.).

We already know that psychopaths’ brains differ structurally from healthy brains. What is new here is that nobody, until now, has examined a population of violent offenders with ASPD to see if we observe differences between ASPD-P and ASPD+P … this now reveals that there is indeed a distinct physical difference in the brain. ASPD+P offenders displayed significantly reduced grey matter volumes in the anterior rostral prefrontal cortex and temporal poles compared to ASPD-P offenders and healthy non-offenders.

Why does that matter? Well, because these areas are important in understanding other people’s emotions and intentions and are activated when people think about moral behaviour. Damage to these areas is associated with impaired empathising with other people, poor response to fear and distress and a lack of ‘self-conscious’ emotions such as guilt or embarrassment.

“Using MRI scans we found that psychopaths had structural brain abnormalities in key areas of their ‘social brains’ compared to those who just had ASPD,:”Dr Nigel Blackwood from the IoP at King’s and lead author of the study. ”This adds to behavioral and developmental evidence that psychopathy is an important subgroup of ASPD with a different neurobiological basis and different treatment needs.

“There is a clear behavioral difference amongst those diagnosed with ASPD depending on whether or not they also have psychopathy. We describe those without psychopathy as ‘hot-headed’ and those with psychopathy as ‘cold-hearted’. The ‘cold-hearted’ psychopathic group begin offending earlier, engage in a broader range and greater density of offending behaviours, and respond less well to treatment programmes in adulthood, compared to the ‘hot-headed’ group. We now know that this behavioural difference corresponds to very specific structural brain abnormalities which underpin psychopathic behaviour, such as profound deficits in empathising with the distress of others.”

Where this leads us is that we can now begin to distinguish between ASPD caused by emotional instability and so aggression is deployed in a reactive way in response to a perceived threat or sense of frustration, and those who have a lack of empathy and remorse, and so use aggression in a planned way to secure what they want. Understanding such a difference matters, because those without the syndrome of psychopathy, and the associated structural brain damage, will benefit from cognitive and behavioural treatments.